微机系统与接口实验考试题目（2014级题目-01）

微机系统与接口实验考试题目（2014级题目-01）

MY8255_A EQU 0600H
MY8255_B EQU 0602H
MY8255_C EQU 0604H
MY8255_CON EQU 0606H

CODE SEGMENT
ASSUME CS:CODE
START:

MOV SI,3000H
MOV AL,00H
MOV [SI],AL             ;清显示缓冲
MOV [SI+1],AL
MOV [SI+2],AL
MOV [SI+3],AL
MOV [SI+4],AL
MOV [SI+5],AL

MOV DX,MY8255_CON       ;写 8255 控制字
MOV AL,89H				;A,B口输出，C口输入，用来读入开关状态
OUT DX,AL

X0:
CALL DIS
MOV DX,MY8255_C
IN AL,DX
AND AL,0C0H				;读取开关K6,K7
CMP AL,00H				;K6K7=00
JZ X1
CMP AL,40H				;K6K7=01
JZ X2
CMP AL,80H				;K6K7=10
JZ X3
CMP AL,0C0H				;K6K7=11
JZ X4
JMP X0

X1:
CALL CLRBUF				;将显存清空
JMP X0
X2:
CALL CLRBUF
MOV SI,3000H
MOV [SI],70H			;"|-"的段码放在第一个显存单元
MOV [SI+1],40H			;"-"的段码放在第二个显存单元

J2:	CALL DIS
CALL CLEAR
CALL DELAY1
;CALL DELAY2
MOV DX,MY8255_C
IN AL,DX
AND AL,0C0H				;读取开关K6,K7
CMP AL,40H
JZ J2					;如果开关状态未改变则一直循环以做到闪烁显示
JMP X0

X3:
CALL CLRBUF
MOV SI,3004H
MOV [SI],40H			;"-"的段码放在第五个显存单元
MOV [SI+1],46H			;"-|"的段码放在第六个显存单元

J3:	CALL DIS
CALL CLEAR
CALL DELAY1
;CALL DELAY2
MOV DX,MY8255_C
IN AL,DX
AND AL,0C0H				;读取开关K6,K7
CMP AL,80H
JZ J3					;如果开关状态未改变则一直循环以做到闪烁显示
JMP X0
X4:
MOV SI,3000H
MOV AL,40H
MOV [SI],AL             ;将"-"的段码放在全部六个显存单元
MOV [SI+1],AL
MOV [SI+2],AL
MOV [SI+3],AL
MOV [SI+4],AL
MOV [SI+5],AL
JMP X0

CLEAR:
MOV DX,MY8255_B         ;清屏子程序
MOV AL,00H
OUT DX,AL
RET

DIS:
PUSH AX                 ;显示子程序，作用为将六个显存中的数据依次取出并送给相应的数码管显示
MOV SI,3000H
MOV DL,7FH				;01 111111
MOV AL,DL

AGAIN:
ROL AL,1		;选择下一个显像管
MOV DL,AL
PUSH DX
MOV DX,MY8255_A
OUT DX,AL
MOV AL,[SI]		;键号

MOV DX,MY8255_B
OUT DX,AL
CALL DELAY		;显示
INC SI			;下一个键号
POP DX
MOV AL,DL

TEST AL,20H
JZ OUT1
MOV DL,AL
JMP AGAIN
OUT1:
POP AX
RET

DELAY:

PUSH CX                  ;短延时子程序，用于显示子程序循环显示六个数码管
MOV CX,04FFH

T1: LOOP T1
POP CX

RET

DELAY1:
PUSH AX
PUSH CX                  ;长延时子程序，用于控制闪烁
MOV CX,0004H
TT1: MOV AX,0FFFFH
TT2: DEC AX
JNZ TT2
LOOP TT1
POP CX
POP AX
RET

DELAY2:
PUSH CX
MOV CX,0FFH

CLRBUF:
MOV SI,3000H
MOV AL,00H
MOV [SI],AL             ;清显示缓冲子程序
MOV [SI+1],AL
MOV [SI+2],AL
MOV [SI+3],AL
MOV [SI+4],AL
MOV [SI+5],AL

RET

CODE ENDS
END START